Swash-plate-type compressor

ABSTRACT

A swash-plate-type compressor of a double-headed-piston configuration, wherein: a front intake chamber is formed set apart from a swash plate chamber so as to be positioned in a narrow space between circumferentially arranged front cylinder bores; and an intake-chamber-communication path is formed in a cylinder block, the intake-chamber-communication path allowing the front intake chamber and a shaft hole to communicate. A front-bore-communication path is formed on the cylinder block, the communication path allowing each of the plurality of front cylinder bores to communicate with the shaft hole. A front rotary valve is provided on a rotating shaft in which a lead-in groove is formed. The lead-in groove allows the intake-chamber communication path and the front-bore communication path to communicate in the stated order, while the lead-in groove rotates integrally with the rotating shaft. In the compact swash-plate-type compressor any decrease in pulsation or intake efficiency is minimized.

TECHNICAL FIELD

The present invention relates to a swash plate compressor including acylinder block having a shaft hole into which a rotary shaft isinserted, and a plurality of cylinder bores located around the shafthole and arranged along a peripheral direction. The cylinder boresrespectively receive pistons.

BACKGROUND ART

For example, Patent Document 1 describes a double-headed piston typeswash plate compressor employing a double-headed piston. As shown inFIG. 11, a swash plate compressor 80 of Patent Document 1 includes acylinder block 81 having three cylinder bores 81 a. A double-headedpiston 82 is accommodated in each cylinder bore 81 a. The cylinder block81 includes a single suction chamber 83, which is arranged between twoadjacent cylinder bores 81 a, and a single discharge chamber 84, whichis arranged at a different location between two adjacent cylinder bores81 a. The suction chamber 83 and the discharge chamber 84 each having anecessary volume to suppress pulsation can be arranged in the cylinderblock 81 by effectively using the region between adjacent cylinder bores81 a. This avoids enlargement of the swash plate compressor 80.

Although not shown in the drawing, in the swash plate compressor 80 ofPatent Document 1, refrigerant is drawn from the suction chamber intothe cylinder bores 81 a when a reed type suction valve opens a suctionport. When refrigerant is drawn through such a suction valve, thesuction valve opens and closes in accordance with the difference inpressure between the interior of the corresponding cylinder bore 81 aand the suction chamber. The suction valve does not open until thepressure in the cylinder bore 81 a decreases to a predeterminedpressure. Thus, the suction valve may not open at the desired timing.This may decrease the suction efficiency.

To prevent the suction efficiency from decreasing, the use of a rotaryvalve that mechanically communicates the suction chamber and cylinderbores is effective for the swash plate compressor 80 that avoidsenlargement.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Laid-Open Patent Publication No. H9-317633

Patent Document 2: Japanese Laid-Open Patent Publication No. 2007-138925

Patent Document 3: Japanese Laid-Open Patent Publication No. 2007-270790

SUMMARY OF THE INVENTION Problems that are to be Solved by the Invention

As shown in FIG. 12, in a swash plate compressor 90 disclosed in PatentDocument 2 that employs a rotary valve, refrigerant is first sent intoan accommodation chamber 93 a (suction chamber) in a front housing 93through a communication groove 98 from a swash plate chamber 99. Thus,to guide the refrigerant to an suction passage 96, which is incommunication with cylinder bores 97, the refrigerant in the fronthousing 93 (accommodation chamber 93 a) is sent toward a cylinder block91 though a supply passage 92 a. More specifically, a rotation shaft 92is must include the supply passage 92 a, which extends from the fronthousing 93 to the cylinder block 91. This lengthens the supply passage92 a in the axial direction. Accordingly, in the swash plate compressor90 of Patent Document 2, the formation of the supply passage 92 aenlarges the swash plate compressor 90 in the axial direction.

As shown in FIG. 13, a swash plate compressor 100 of Patent Document 3that also employs a rotary valve includes a rotation shaft 101 having asupplying passage 102 formed therein and a conducting hole 101 a forcommunicating inside and outside of the supplying passage 102. Acylinder block 104 includes a suction recess 105 located around therotation shaft 101. The conducting hole 101 a communicates a swash platechamber 106 with the supplying passage 102 through the suction recess105.

In the Patent Document 3, when the suction recess 105 and the conductinghole 101 a are in communication with the swash plate chamber 106,refrigerant in the swash plate chamber 106 flows in the supplyingpassage 102 through the suction recess 105 and the conducting hole 101a. The refrigerant further flows from the supplying passage 102 tocylinder bores 108 through a rotary valve 107. Also in Patent Document3, the conducting hole 101 a is formed in the rotation shaft 101 so thatthe rotation shaft 101 is elongated in the axial direction. The suctionrecess 105 is formed in the cylinder block 104 so that body of the swashplate type compressor 100 enlarges in the axial direction. The rotationshaft 101 having the supplying passage 102 needs to be enlarged in aradial direction to ensure the strength in the rotation shaft 101. Thisenlarges the body of the swash plate type compressor in the radialdirection.

As discussed above, in the swash plate compressor 90 and 100, whichemploys conventional rotary valve, each of the swash plate chambers 99and 106 functions as suction chamber. This complicates the structure ofthe rotary valve 107 and enlarges the rotary valve 107. This alsoenlarges the body of the swash plate compressor 90 and 100.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a small swash platecompressor, which suppresses pulsation and prevents the suctionefficiency from decreasing.

Means for Solving the Problem

To achieve the foregoing object, one aspect of the present invention isa swash plate compressor including a cylinder block, a swash plate,pistons, a rotation shaft and a rotary valve. The cylinder blockincludes a shaft hole, cylinder bores, a swash plate chamber and asuction chamber. The shaft hole extends through the cylinder block. Thecylinder bores are arranged along a circumferential direction around theshaft hole. The suction chamber is arranged in a space between theadjacent cylinder bores and is separated from the swash plate chamber.The swash plate is accommodated in the swash plate chamber. The pistonsare connected with the swash plate and respectively arranged in thecylinder bores. The rotation shaft is arranged in the shaft hole andoperative to rotate integrally with the swash plate. The rotary valve isprovided with the rotation shaft to rotate integrally with the rotationshaft. The cylinder block includes a suction chamber communicationpassage that defines a communication path between the suction chamberand the shaft hole, and bore communication passages that defineindependent communication paths between the cylinder bores and the shafthole. The rotary valve rotates integrally with the rotation shaft toprovide sequential communication between the suction chambercommunication passage and the bore communication passages.

Accordingly, the suction chamber and cylinder bores are arranged aroundthe rotary valve along a circumferential direction. Thus, when therotary valve is employed, body size of the rotary valve and the swashplate compressor are prevented from enlarged. In addition, since therotary valve is employed, suction efficiency is prevented from beingreduced as compared to when a suction valve is employed.

Preferably, the suction chamber includes a plurality of suctionchambers. Each of the plurality of suction chambers is arranged betweena circumferentially adjacent pair of the cylinder bores. The suctionchamber communication passage includes a plurality of suction chambercommunication passages that provide independent communication betweenthe suction chambers and the shaft hole.

Accordingly, the suction chamber and cylinder bores are alternatelyarranged around the rotary valve along a circumferential direction. Inorder to communicate the cylinder bore and the suction chamber via therotary valve, the intake passage is simply formed at a portion of therotary valve to extend in the circumferential direction.

This simplifies the shape of the front rotary valve and thereforefurther shortens an axial length of the front rotary valve.

Preferably, the cylinder block includes a plurality of dischargechambers. Each of the discharge chambers is arranged in a space betweenadjacent cylinder bores.

Accordingly, when the cylinder blocks are thermally expanded due to theheat of the refrigerant discharged to the discharge chambers, thermallyexpanded portions are uniformly distributed in the cylinder blocks alongthe radial direction. This prevents each cylinder bore and each pistonfrom adversely affected by a thermal expansion.

Preferably, the discharge chambers are arranged outward in a radialdirection of the cylinder block from the suction chambers.

Preferably, the cylinder block includes a suction port to which anexternal pipe is connected, and a suction passage that providescommunication between the suction port and the suction chamber. Thesuction passage is separated from the swash plate chamber.

Accordingly, the rotation shaft having a rotary valve receives heatgenerated by sliding friction due to the rotation of the rotation shaft.In a suction passage from the suction port via the front suction chamberto the front cylinder bore, heat exchange between the refrigerant andthe rotation shaft is only carried out when the refrigerant passesthrough the rotary valve. In addition, an axial length of the rotaryvalve is shortened so that the refrigerant is sufficiently preventedfrom being heated. This improves the suction efficiency.

Preferably, the suction chamber communication passage is a recess formedin an inner wall of the shaft hole. The recess includes an open end incommunication with the swash plate chamber. A thrust bearing is arrangedbetween the swash plate and the open end of the recess. The thrustbearing closes the open end of the recess.

Accordingly, the suction chamber communication passage is formedtogether with when the cylinder block is molded. This reduces time formanufacturing the cylinder block as compared with the case in which thecylinder block is molded and then the cylinder block is subjected to acutting work by a drill or the like to form the suction chambercommunication passage.

Preferably, the suction chamber communication passage includes a firstrecess and a second recess. The first recess is formed in an inner wallof the suction chamber. The first recess includes an open end, whichopens toward an end face of the cylinder block in an axial direction.The second recess is formed in an inner wall of the shaft hole. Thesecond recess includes an open end in communication with the swash platechamber. A thrust bearing is arranged between the swash plate and theopen end of the second recess. The thrust bearing closes the open end ofthe second recess.

Accordingly, the suction chamber communication passage is formedtogether with when the cylinder block is molded. In addition, the sizeof an opening between the suction chamber communication passage and theswash plate chamber is reduced so that the size of the thrust bearingserving as a closing member can be reduced.

Preferably, the cylinder bores are three cylinder bores.

This sufficiently ensures volume of the suction chamber, and suppressesthe pulsation.

Effects of the Invention

The present invention provides a swash plate compressor, which isdecreased in size while suppresses pulsation and suction efficiency frombeing lowered.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a double-headed piston typeswash plate compressor according to a first embodiment of the presentinvention taken along line 1-1 in FIG. 3.

FIG. 2 is a cross-sectional view showing the double-headed piston typeswash plate compressor according to the first embodiment taken alongline 2-2 in FIG. 3.

FIG. 3 is a cross-sectional view showing a front discharge chamber and afront suction chamber taken along line 3-3 in FIG. 1.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1 showinga front cylinder bore, the front suction chamber and the front dischargechamber.

FIG. 5 is a partial cross-sectional view showing a double-headed pistontype swash plate compressor according to a second embodiment of thepresent invention.

FIG. 6 is a development view showing a rotary valve and inside of ashaft hole of FIG. 5.

FIG. 7( a) is a cross-sectional view taken along line 7 a-7 a of FIG. 5showing a cylinder block as viewed from a front suction chamber.

FIG. 7( b) is a cross-sectional view taken along line 7 b-7 b of FIG. 5showing a cylinder block as viewed from a shaft hole.

FIG. 8 is a partial cross-sectional view showing a double-headed pistontype swash plate compressor of another example.

FIG. 9 is a cross-sectional view showing a double-headed piston typeswash plate compressor of another example.

FIG. 10 is a development view showing a front rotary valve of anotherexample.

FIG. 11 is a diagram showing a Patent Document 1.

FIG. 12 is a diagram showing a Patent Document 2.

FIG. 13 is a diagram showing a Patent Document 3.

EMBODIMENTS OF THE INVENTION First Embodiment

A first embodiment of the present invention that embodies a swash platecompressor in a double-headed piston type swash plate compressor 10 willnow be described with reference to FIGS. 1 to 4.

As shown in FIGS. 1 and 2, a double-headed piston type swash platecompressor 10 (hereinafter simply referred to as the compressor 10)includes a housing H. A cylinder block 11, which is located at a frontside (left side as viewed in FIG. 1), is coupled to a front housing 13with a front valve/port formation body 15 arranged in between. Acylinder block 12, which is located at a rear side (right side as viewedin FIG. 1), is coupled to a rear housing 14 with a rear valve/portformation body 16 arranged in between. The housing H is formed by thetwo cylinder blocks 11 and 12 and the front and rear housings 13 and 14sandwiching the cylinder blocks 11 and 12.

A rotation shaft 22 is inserted into shaft holes 11 a and 12 a that arerespectively formed in the cylinder blocks 11 and 12. The rotation shaft22 is supported to be rotatable by sealing surfaces defined on the wallsurfaces of the shaft holes 11 a and 12 a. The rotation shaft 22 isinserted through insertion holes 15 d and 16 d respectively formed inthe centers of the front valve/port formation body 15 and the rearvalve/port formation body 16. At an end of the rotation shaft 22projecting from the front valve/port formation body 15, a lip type shaftseal 23 hermetically seals the space between the front housing 13 andthe rotation shaft 22. The shaft seal 23 is accommodated in anaccommodation chamber 13 c defined between the inner wall surface of thefront housing 13 and the circumferential surface of the rotation shaft22.

A swash plate 24, which rotates integrally with the rotation shaft 22,is fixed to the rotation shaft 22. The swash plate 24 is arranged in thecylinder block 11, 12 and accommodated in a swash plate chamber 25,which is formed between the cylinder blocks 11 and 12. A thrust bearing26 is arranged between the front cylinder block 11 and an annular base24 a of the swash plate 24. A thrust bearing 27 is arranged between therear cylinder block 12 and the base 24 a of the swash plate 24. Therotation shaft 22 has an axis L. The thrust bearings 26 and 27 sandwichthe swash plate 24 to restrict movement of the swash plate 24 along theaxial direction. The thrust bearings 26 and 27 are pushed respectivelytoward open ends of the shaft holes 11 a and 12 a in the cylinder blocks11 and 12.

As shown in FIG. 4, three front cylinder bores 28 are arranged aroundthe rotation shaft 22 in the front cylinder block 11. Further, referringto FIG. 1, three rear cylinder bores 29 are arranged around the rotationshaft 22 in the rear cylinder block 12. Each front cylinder bore 28 ispaired with one of the rear cylinder bores 29. The front and rearcylinder bores 28 and 29 in each pair are aligned with each other in theaxial direction (front to rear direction) in which the axis L extends. Adouble-headed piston 30 serving as a piston is inserted in each pair ofthe cylinder bore 28 and 29. The front cylinder bore 28 is closed by thefront valve/port formation body 15 and the corresponding double-headedpiston 30, and the rear cylinder bore 29 is closed by the rearvalve/port formation body 16 and the corresponding double-headed piston30.

Two shoes 31 arranged on opposite sides of the swash plate 24 transmitthe rotational movement of the swash plate 24, which rotates integrallywith the rotation shaft 22, to the double-headed pistons 30. Thisreciprocates each double-headed piston 30 in the corresponding front andrear cylinder bores 28 and 29. A front compression chamber 28 a isdefined in the front cylinder bore 28 by the double-headed piston 30 andthe front valve/port formation body 15, and a rear compression chamber29 a is defined in the rear cylinder bore 29 by the double-headed piston30 and the rear valve/port formation body 16.

The front housing 13 and cylinder block 11 include three front suctionchambers 17, which surround the rotation shaft 22 and extend through thefront valve/port formation body 15 in. As shown in FIG. 4, each of thethree front suction chambers 17 are arranged between the front cylinderbores 28 that are circumferentially adjacent around the shaft hole 11 a.The three front suction chambers 17 are arranged at equal interval atthe outer side of the shaft hole 11 a.

As shown in FIGS. 1 and 2, one of the three front suction chambers 17has a longer length in the axial direction of the rotation shaft 22 anda greater volume than the other two front suction chambers 17. As shownin FIG. 3, each of the three front suction chambers 17 is incommunication with the accommodation chamber 13 c of the front housing13. Thus, the three front suction chambers 17 are in communication withone another about the accommodation chamber 13 c. This forms a singlecontinuous space.

As shown in FIGS. 1 and 3, a front discharge chamber 28 b is definedaround the rotation shaft 22 between the front housing 13 and the frontvalve/port formation body 15. The front discharge chamber 28 b is aregion into which the refrigerant from the three front compressionchambers 28 a is discharged. Further, the front discharge chamber 28 bis annular and defined in the peripheral portion of the front housing13.

In the front discharge chamber 28 b, each portion facing one of thefront compression chambers 28 a through the front valve/port formationbody 15 forms an opening. In the front discharge chamber 28 b, theportions facing the front compression chambers 28 a are in communicationwith one another through passages. This forms a single continuous space.

As shown in FIGS. 3 and 4, three front discharge chambers 40, which arein communication with the front discharge chamber 28 b, are defined inthe cylinder block 11. The front discharge chambers 40 extend from thefront cylinder block 11 and through the front valve/port formation body15. The three front discharge chambers 40 are arranged around therotation shaft 22. Each front discharge chamber 40 is formed between thefront cylinder bores 28 that are adjacent in the circumferentialdirection of the shaft hole 11 a. Further, the front discharge chambers40 are located outward in the radial direction of the cylinder block 11from the front suction chambers 17.

As shown in FIGS. 1 and 3, the front valve/port formation body 15includes discharge ports 15 a, which are arranged in correspondence withthe front cylinder bores 28, and discharge valves 15 b, which arearranged in correspondence with the discharge ports 15 a. Further, thefront valve/port formation body 15 includes retainers 15 c, whichrestrict the open amount of the corresponding discharge valves 15 b.

The rear structure will now be described.

As shown in FIGS. 1 and 2, three rear suction chambers 18 are arrangedaround the rotation shaft 22 (shaft hole 12 a) and extend through therear valve/port formation body 16 in the rear housing 14 and thecylinder block 12. In the same manner as the front side, each of thethree rear suction chambers 18 is arranged in a space between the rearcylinder bores 29 that are adjacent in the circumferential direction ofthe shaft hole 12 a. One of the three rear suction chambers 18 has alonger length in the axial direction of the rotation shaft 22 and agreater volume than the other two rear suction chambers 18.

A rear housing suction chamber 19 is defined between a central part ofthe rear housing 14 and the rear valve/port formation body 16. The threerear suction chambers 18 are in communication with one another in therear housing suction chamber 19. Thus, the three rear suction chambers18 are in continuous communication with one another about the rearhousing suction chamber 19. Each front suction chamber 17 is paired withone of the rear suction chambers 18. The front suction chamber 17 andrear suction chamber 18 in each pair are aligned in the front to reardirection in which the axis L extends. The front suction chamber 17 andrear suction chamber 18 are formed at opposite sides of the swash plate24 in the cylinder blocks 11 and 12.

An annular rear discharge chamber 29 b is defined around the rotationshaft 22 between the rear housing 14 and the rear valve/port formationbody 16. The rear discharge chamber 29 b is a region into which therefrigerant from the three rear compression chambers 29 a is discharged.Further, the rear discharge chamber 29 b is defined at the outer side ofthe rear housing suction chamber 19. In the rear discharge chamber 29 b,each portion facing one of the rear cylinder bores 29 through the rearvalve/port formation body 16 forms an opening having a size thatconforms to the circular rear compression chamber 29 a. In the reardischarge chamber 29 b, the portions facing the rear cylinder bores 29are in communication with one another through passages. This forms asingle continuous space.

The cylinder block 12 includes three rear discharge chamber 42, whichare in communication with the rear discharge chamber 29 b. The reardischarge chambers 42 extend from the rear housing 14 through the rearvalve/port formation body 16 and to the rear cylinder block 12. Thethree rear discharge chambers 42 are arranged around the shaft hole 12 aand formed between the rear cylinder bores 29 that are adjacent in thecircumferential direction of the shaft hole 12 a. The rear dischargechambers 42 are formed outward in the radial direction of the cylinderblock 12 from the rear suction chambers 18. Each front discharge chamber28 b is paired with one of the rear discharge chambers 29 b. The frontdischarge chamber 28 b and rear discharge chamber 29 b in each pair arealigned in the front to rear direction in which the axis L extends.

As shown in FIG. 1, the rear valve/port formation body 16 includesdischarge ports 16 a, which are arranged in correspondence with the reardischarge chambers 29 b, and discharge valves 16 b, which are arrangedin correspondence with the discharge ports 16 a. Further, the rearvalve/port formation body 16 includes retainers 16 c, which restrict theopen amount of the discharge valves 16 b.

A suction passage 43 is formed in the cylinder blocks 11 and 12. Thesuction passage 43 has a front opening, which is in communication withthe front suction chamber 17 having the largest volume, and a rearopening, which is in communication with the rear suction chamber 18having the largest volume. Further, a suction port 44 is formed in thefront cylinder block 11. The suction port 44 has one end that opens inthe outer surface of the cylinder block 11 and another end that opens inthe wall surface of the suction passage 43. An external pipe 32 of anexternal refrigerant circuit that is arranged outside the compressor 10is connected to one open end of the suction port 44. The suction passage43 is formed in the cylinder blocks 11 and 12 and separated from theswash plate chamber 25.

The suction passage 43 is formed in communication with the front andrear suction chambers 17 and 18 having the largest volume. Thus, thesuction passage 43 is sandwiched in the axial direction by the frontdischarge chamber 40 and the rear discharge chamber 42, which arelocated at the outer sides of the suction chambers 17 and 18.

As shown in FIG. 2, a discharge passage 45 is formed in the cylinderblocks 11 and 12. The discharge passage 45 has a front opening, which isin communication with one of the three front discharge chambers 40, anda rear opening, which is in communication with one of the three reardischarge chambers 42. Further, a discharge port 46 is formed in thecylinder block 11. The discharge port 46 has one end that opens in theouter surface of the cylinder block 11 and another end that opens in thewall surface of the discharge passage 45. The external pipe 33 of theexternal refrigerant circuit that is arranged outside the compressor 10,is connected to the discharge port 46.

As shown in FIG. 3, in the cylinder blocks 11 and 12, the dischargepassage 45 is separated in the circumferential direction of the cylinderblocks 11 and 12 from the suction passage 43. More specifically, thefront discharge chamber 40 and rear discharge chamber 42 sandwiching thedischarge passage 45 in the axial direction is separated in thecircumferential direction from the front discharge chamber 40 and reardischarge chamber 42 sandwiching the suction passage 43 in the axialdirection.

When forming a refrigerating cycle for a vehicle air conditioner withthe compressor 10, the external refrigerant circuit connects thedischarge port 46 and the suction port 44 of the compressor 10 via theexternal pipes 32 and 33. The external refrigerant circuit includes acondenser, an expansion valve, and an evaporator, which are arranged inorder from the discharge port 46 of the compressor 10 in the externalrefrigerant circuit.

The suction structure of the compressor 10 will now be described.

First, a front suction structure will be described. As shown in FIG. 4,suction chamber communication passages 50 a communicating the frontsuction chambers 17 and the shaft hole 11 a are formed in the cylinderblock 11. Each suction chamber communication passage 50 a has one endthat opens in the corresponding front suction chamber 17 and another endthat opens in the sealing surface of the wall defining the shaft hole 11a. The suction chamber communication passages 50 a formed in thecylinder block 11 extend slightly inclined relative to the radialdirection of the cylinder block 11.

Front bore communication passages 50 b communicating the shaft hole 11 aand the front cylinder bores 28 are formed in the cylinder block 11.Each front bore communication passage 50 b has one end that opens in thesealing surface of the wall defining the shaft hole 11 a and another endthat opens in the corresponding front cylinder bore 28. The suctionchamber communication passages 50 a and front bore communicationpassages 50 b are alternately arranged in the circumferential directionof the shaft hole 11 a.

As shown in FIGS. 1 and 4, an intake groove 22 a is formed in thecircumferential surface of the front side of the rotation shaft 22. Theintake groove 22 a is recessed in the circumferential surface of therotation shaft 22, which is a solid shaft, at the side closer to thefront housing 13. The intake groove 22 a opens towards the sealingsurface of the wall defining the shaft hole 11 a and is independentlycommunicable with the suction chamber communication passages 50 a andthe front bore communication passages 50 b. Rotation of the rotationshaft 22 changes the position of the intake groove 22 a. Thismechanically switches the suction chamber communication passages 50 aand front bore communication passages 50 b that come into communicationwith the intake groove 22 a.

The portion of the rotation shaft 22 surrounded by the sealing surfaceforms a front rotary valve RF, which is formed integrally with therotation shaft 22. The intake groove 22 a communicates one of thesuction chamber communication passage 50 a and the front borecommunication passage 50 b that is adjacent in the circumferentialdirection of the shaft hole 11 a. As the rotation shaft 22 rotates, thesuction chamber communication passage 50 a and front bore communicationpassage 50 b that are independently in communication through the intakegroove 22 a draw in refrigerant from the corresponding front suctionchamber 17 to the adjacent front cylinder bore 28. In the presentembodiment, the intake groove 22 a serves as a supplying passage, whichcommunicates the front cylinder bore 28 and the front suction chamber 17in the front rotary valve RF.

The rear intake structure will now be described.

As shown in FIGS. 1 and 2, rear intake passages 51 communicating therear cylinder bores 29 and the shaft hole 12 a are formed in thecylinder block 12. Each rear intake passage 51 has one end that opens inthe corresponding rear cylinder bore 29 and another end that opens inthe sealing surface of the wall defining the shaft hole 12 a. A supplypassage 22 b is formed in the circumferential surface of the rear sideof the rotation shaft 22. The supply passage 22 b has one end that opensin the rear housing suction chamber 19 of the rear housing 14 andanother end that is communicable with the rear intake passages 51.Rotation of the rotation shaft 22 changes the position of the supplypassage 22 b. This mechanically switches the rear intake passages 51that come into communication with the supply passage 22 b. The portionof the rotation shaft 22 surrounded by the sealing surface forms a rearrotary valve RR, which is formed integrally with the rotation shaft 22.

The operation of the compressor 10 will now be described.

Refrigerant is drawn through the suction port 44 into the suctionpassage 43 and supplied to each front suction chamber 17 and each rearsuction chamber 18. When each front cylinder bore 28 performs the intakestroke, one of the suction chamber communication passages 50 a and theadjacent front bore communication passage 50 b come into communicationthrough the intake groove 22 a of the front rotary valve RF, as shown inFIG. 4. The refrigerant is then drawn from the front suction chamber 17through the front rotary valve RF into the corresponding front cylinderbore 28.

As the rotation shaft 22 further rotates, the intake groove 22 a goesout of communication with the suction chamber communication passage 50a. In this state, the suction chamber communication passage 50 a and thefront bore communication passage 50 b are not in communication with eachother, and the front cylinder bore 28 is closed. Then, the frontcylinder bore 28 performs the compression stroke and discharge stroke.The refrigerant in the front compression chamber 28 a is forced throughthe discharge valve 15 b from the discharge port 15 a and discharged tothe front discharge chamber 28 b. The refrigerant discharged to thefront discharge chamber 28 b flows out of the front discharge chamber 40through the discharge passage 45 and the discharge port 46 and into theexternal refrigerant circuit.

At the rear side, when each rear cylinder bore 29 performs the intakestroke in a state in which refrigerant is supplied to the rear housingsuction chamber 19, the supply passage 22 b, which is in communicationwith the rear housing suction chamber 19 in the rear rotary valve RR,comes into communication with one or two rear intake passage 51. Thissupplies refrigerant to the rear intake passage 51 from the rear housingsuction chamber 19 through the rear rotary valve RR, and the refrigerantis drawn into the rear cylinder bore 29, which is in communication withthe rear intake passage 51.

As the rotation shaft 22 further rotates, the supply passage 22 b goesout of communication with the rear intake passage 51. In this state, therear intake passage 51 and the rear housing suction chamber 19 are notin communication with each other, and the rear cylinder bore 29 isclosed.

Then, the rear cylinder bore 29 performs the compression stroke and thedischarge stroke. The refrigerant in the rear compression chamber 29 ais forced through the discharge valve 16 b from the discharge port 16 aand discharged to the rear discharge chamber 29 b. The refrigerantdischarged to the rear discharge chamber 29 b flows out of the reardischarge chamber 42 through the discharge passage 45 and the dischargeport 46 and into the external refrigerant circuit.

Accordingly, the present embodiment has the advantages described below.

(1) In the double-headed piston type swash plate compressor 10, thethree front cylinder bores 28 are formed around the shaft hole 11 a ofthe cylinder block 11, and each front suction chamber 17 is arrangedbetween the front cylinder bores 28 that are adjacent to each other.That is, the front cylinder bores 28 and the front suction chambers 17are alternately arranged around the shaft hole 11 a. In addition, thesuction chamber communication passages 50 a, which communicates frontsuction chambers 17 with the shaft hole 11 a, and the front borecommunication passages 50 b, which communicates the front cylinder bores28 with the shaft hole 11 a, are formed in the cylinder block 11. Thesuction chamber communication passages 50 a and the front borecommunication passages 50 b are alternately arranged in thecircumferential direction of the shaft hole 11 a. In the cylinder block11, the refrigerant in each front suction chamber 17 is directly drawninto the intake groove 22 a through the corresponding suction chambercommunication passage 50 a, and then drawn in the front cylinder bore 28through the front bore communication passage 50 b.

Accordingly, in order to communicate the front cylinder bore 28 and thecircumferentially adjacent front suction chamber 17 via the rotary valveRF, the intake groove 22 a is simply formed at a portion of the rotaryvalve RF to extend in the circumferential direction. This simplifies theshape of the front rotary valve RF and therefore shortens an axiallength of the front rotary valve RF. Thus, the compressor 10 isprevented from enlarging the body size in both the axial direction andthe radial direction if the front rotary valve RF is provided in thecompressor 10, which includes the suction chamber 17 formed in thecylinder block 11. In this manner, a rotary valve is used instead of asuction valve to draw refrigerant, and the front cylinder bores 28 aremechanically communicated with the front suction chamber 17. Thisprevents the suction efficiency from decreasing and is in contrast witha suction valve. In addition, three front suction chambers 17 are formedin the cylinder block 11. This sufficiently ensures volume of thesuction chamber, and suppresses the pulsation.

(2) Each front suction chamber 17 is formed between the front cylinderbores 28 that are adjacent in the circumferential direction of the shafthole 11 a. In the cylinder block 11, the suction chamber communicationpassages 50 a communicate the front suction chambers 17 and the intakegroove 22 a of the front rotary valve RF. Refrigerant is directly drawnfrom each front suction chamber 17 into the intake groove 22 a throughthe corresponding suction chamber communication passage 50 a. Thus, therefrigerant does not need to be drawn into the suction pressure regionof the front housing 13, and the intake groove 22 a does not need toextend from the front housing 13 to the cylinder block 11 in therotation shaft 22. In this manner, the rotation shaft 22 is supported bythe shaft hole 11 a (sealing surface) at the front and rear of theintake groove 22 a in the axial direction, the bearing area for therotation shaft 22 is ensured, and the abrasion resistance is increased.

(3) In the same manner as the front suction chambers 17, each rearsuction chamber 18 is formed between adjacent rear cylinder bores 29around the rotation shaft 22. Thus, the suction chambers 17 and 18 arearranged in the radial direction of the cylinder blocks 11 and 12 at thefront and rear sides. This avoids enlargement of the compressor 10 inthe axial direction.

(4) The front housing 13 includes the front discharge chamber 28 b, andthe rear housing 14 includes the rear discharge chamber 29 b. The threefront discharge chambers 40 are in communication with the frontdischarge chamber 28 b, and the three rear discharge chambers 42 are incommunication with the rear discharge chambers 29 b. Each of thedischarge chambers 40 and 42 is arranged between adjacent cylinder bores28 and 29. Thus, the discharge chambers 40 and 42 each having largevolume can be ensured, and the pulsation can be further reduced.

(5) The discharge chambers 40 and 42 are arranged at the outer side ofthe suction chambers 17 and 18 in the radial direction of the cylinderblocks 11 and 12. Thus, when the cylinder blocks 11 and 12 are thermallyexpanded due to the heat of the refrigerant discharged to the dischargechambers 40 and 42, thermally expanded portions are uniformlydistributed in the cylinder blocks 11 and 12 along the radial direction.This prevents the double-headed piston 30 from adversely affected by athermal deformation of the cylinder bores 28 and 29.

(6) Each of the discharge chambers 40 and 42 is between the cylinderbores 28 and 29. Thus, even when the cylinder blocks 11 and 12 arethermally expanded due to the high-temperature refrigerant discharged tothe discharge chambers 40 and 42, thermally expanded portions are evenlydistributed in the circumferential direction of the cylinder blocks 11and 12. This prevents the double-headed piston 30 from being adverselyaffected by a thermal deformation of the cylinder bores 28 and 29.

(7) The suction port 44 is formed in the cylinder block 11, and thesuction passage 43, which communicates the front suction chamber 17 andthe rear suction chamber 18, is formed in the cylinder blocks 11 and 12.Thus, when refrigerant is drawn into the suction chambers 17 and 18, therefrigerant does not flow through the swash plate chamber 25. Thisprevents the refrigerant that is drawn into the suction chambers 17 and18 from being heated by the high-temperature blow-by gas and therotation shaft 22 heated by a sliding friction in the swash platechamber 25.

(8) Pairs of the front suction chamber 17 and rear suction chamber 18are formed in the axial direction, and pairs of the front dischargechamber 40 and rear discharge chamber 42 are formed in the axialdirection. Further, the front rotary valve RF is used for the frontcylinder bores 28, and the rear rotary valve RR is used for the rearcylinder bores 29. Thus, the suction structure is the same at the frontand rear sides. This prevents the occurrence of vibration and noise thatwould be caused by a difference in the suction structure between thefront and rear sides.

(9) Each front suction chamber 17 is formed between front cylinder bores28, which are adjacent in the circumferential direction around the shafthole 11 a. The suction chamber communication passages 50 a, whichcommunicate the front suction chambers 17 and the intake groove 22 a ofthe front rotary valve RF, and the front bore communicating passages 50b, which communicating the intake groove 22 a and the front cylinderbores 28, are formed in the cylinder block 11. Refrigerant is drawn fromeach front suction chamber 17 into the corresponding front cylinder bore28 through the suction chamber communication passage 50 a, the intakegroove 22 a, and the front bore communication passage 50 b. Thus,refrigerant is drawn from the front suction chamber 17 to the frontcylinder bore 28 within the cylinder block 11. This reduces a contactingarea between the refrigerant and the intake groove 22 a compared to whenthe refrigerant is drawn into the front cylinder bores 28 through agroove, which extends into the front housing 13 and the swash platechamber 25. This reduces suction heating that would be caused when thecontacting area is large, and prevents the suction efficiency fromdecreasing.

(10) The rotation shaft 22 receives heat generated by sliding frictionbetween the rotation shaft 22 and the shaft holes 11 a and 12 a or thelike. In a suction passage from the suction port 44 via the frontsuction chamber 17 to the front cylinder bore 28, heat exchange iscarried out between the refrigerant and the rotation shaft 22 throughthe front rotary valve RF when the refrigerant passes through the intakegroove 22 a. The intake groove 22 a has a short length so that therefrigerant is sufficiently prevented from being heated. This improvesthe suction efficiency.

Second Embodiment

Next, a second embodiment of the present invention will be describedwith reference to FIGS. 5 to 7. The same constituents as those in thefirst embodiment are given the same reference numerals and overlappingdescription thereof is omitted or simplified.

As shown in FIGS. 5 and 7( a), a first recess 60 corresponding to eachfront suction chamber 17 is formed at a portion of a first end face 11b, which is a surface of a cylinder block 11 closer to a front housing13, located outside of a shaft hole 11 a. The first recess 60 is formedin the cylinder block 11 to extend from an inner wall of each frontsuction chamber 17 in a radial direction. One end of the first recess 60opens toward the first end face 11 b, which is a surface of the cylinderblock 11 in an axial direction, and is connected with an open end ofeach front suction chamber 17. The other end of the first recess 60 islocated in the middle of the front suction chamber 17 in the axialdirection, and does not extend through the cylinder block 11 in theaxial direction. The first recess 60 is depressed from the first endface 11 b toward a second end face 11 c.

As shown in FIGS. 5 and 7( b), a second recess 61 corresponding to eachfront suction chamber 17 is formed at the second end face 11 c, which isa surface of the cylinder block 11 closer to the front housing 13 a. Thesecond recess 61 is formed in the cylinder block 11 to extend from theinner wall of each front suction chamber 17 in the radial direction. Oneend of the second recess 61 opens toward the second end face 11 c of thecylinder block 11, and is connected with an open end of the shaft hole11 a. The other end of the second recess 61 is located in the middle ofthe shaft hole 11 a in the axial direction, and does not extend throughthe cylinder block 11 in the axial direction. The second recess 61 isdepressed from the second end face 11 c toward the first end face 11 b.An open end of the second recess 61 closer to the second end face 11 c(closer to a swash plate chamber 25) is closed by a thrust bearing 26.

In the cylinder block 11, the first recess 60 and the second recess 61are connected and in communication with each other thereby forming asuction chamber communication passage 62. One end of the suction chambercommunication passage 62 is defined by an open end of the first recess60 closer to the front suction chamber 17, and the other end of thesuction chamber communication passage 62 is defined by an open end ofthe second recess 61 closer to the shaft hole 11 a. The front suctionchamber 17 and an intake groove 22 a are communicable through thesuction chamber communication passage 62. An open end of the suctionchamber communication passage 62 closer to the swash plate chamber 25 isclosed by the thrust bearing 26, and a clearance between the suctionchamber communication passage 62 and the swash plate chamber 25 issealed. The first recess 60 and the second recess 61 are formed togetherwith the front suction chamber 17 when the cylinder block 11 is molded.

FIG. 6 is a diagram showing a front rotary valve RF developed in acircumferential direction. An outline shown by a solid line indicates aperipheral surface of the front rotary valve RF and the shaft hole 11 a,which receives and supports the front rotary valve RF. The intake groove22 a is shown in the outline. In FIG. 6, dashed-two dotted lineindicates a front bore communication passage 50 b and the suctionchamber communication passage 62 (an overlapping region between thefirst recess 60 and the second recess 61). The front bore communicationpassage 50 b opens toward the shaft hole 11 a and communicates with eachfront cylinder bore 28. The suction chamber communication passage 62opens toward the shaft hole 11 a and communicates with each frontsuction chamber 17.

As shown in FIG. 6, the front bore communication passage 50 b and thesuction chamber communication passage 62 are alternately arranged in thecircumferential direction of the shaft hole 11 a. In order tocommunicate the suction chamber communication passage 62 and the frontbore communication passage 50 b via the intake groove 22 a, the intakegroove 22 a is formed at a portion of the rotation shaft 22 and extendsin the circumferential direction.

Accordingly, the second embodiment has the advantages described below inaddition to the same advantages of (1) to (10) of the first embodiment.

(11) The suction chamber communication passage 62 has a rectangularshape axially elongated. Accordingly, the suction chamber communicationpassage 62 and the front bore communication passage 50 b are alternatelyarranged in the shaft hole 11 a and separate from each other so as toensure sealing ability therebetween. Thus, in order to communicate thefront cylinder bore 28 and the circumferentially adjacent front suctionchamber 17 via the rotary valve RF, the suction chamber communicationpassage 62 and the adjacent front bore communication passage 50 b onlyhave to communicate with each other by the intake groove 22 a. For this,the intake groove 22 a is simply formed at a portion of the rotary valveRF and extends in the circumferential direction. This simplifies theshape of the front rotary valve RF formed in the rotation shaft 22 andtherefore shortens an axial length of the front rotary valve RF. Thus,the compressor 10 is prevented from enlarging the body size in the axialdirection when the front rotary valve RF is provided in the compressor10, which includes the suction chamber 17 formed in the cylinder block11.

(12) The suction chamber communication passage 62 is formed togetherwith the front suction chamber 17 when the cylinder block 11 is molded.This reduces time for manufacturing the cylinder block 11 as comparedwith the case in which the cylinder block 11 is molded and then thecylinder block 11 is subjected to a cutting work by a drill or the liketo form the suction chamber communication passage 62.

(13) The suction chamber communication passage 62 is formed by combiningthe first recess 60 extending from the first end face 11 b and thesecond recess 61 extending from the second end face 11 c. Thissuppresses an opening area of the second recess 61 as compared with thecase in which the suction chamber communication passage is formed onlyby the second recess 61. Thus, the open end of the second recess 61 canbe closed by the thrust bearing, which is relatively small in size.

The first and second embodiments may be varied as described hereafter.

In the embodiment described above, the suction chamber communicationpassage 62 is formed by combining the first recess 60 extending from thefirst end face 11 b and the second recess 61 extending from the secondend face 11 c, but is not limited to this. As shown in FIG. 8, in casethat the thrust bearing 26 has a diameter, which is sufficiently large,the suction chamber communication passage may be formed only by a secondrecess 66 extending from a second end face 11 c of a cylinder block 11.The second recess 66 enables a front suction chamber 17 to directlycommunicate with an intake groove 22 a.

As shown in FIG. 9, an intake pathway for drawing refrigerant gas to thefront cylinder bore 28 may have a pathway passing through an in-shaftpassage 65 and in communication with the rear housing suction chamber19, in addition to a pathway, which extends from the suction chambercommunication passage 62 to the front bore communication passage 50 bvia the front rotary valve RF. According to this configuration,refrigerant is drawn not only through the pathway extending from therear housing suction chamber 19 via the in-shaft passage 65 but alsothrough the pathway extending from the front suction chamber 17 to thefront cylinder bore 28 via the suction chamber communication passage 62.This reduces size of the diameter of the in-shaft passage 65. Thus, therotation shaft 22 and the rotary valve are reduced in size in thediameter direction, and the body of the entire compressor 10 is reducedin size.

In the embodiment described above, rotary valves are used at the frontand rear sides to drawn refrigerant. However, the rear side may use asuction valve instead of the rotary valve.

In the embodiment described above, at the rear side, refrigerant of therear suction chambers 18 is collected in the rear housing suctionchambers 19. Then, the refrigerant is drawn from the rear housingsuction chambers 19 into the rear cylinder bores 29 through the rearrotary valve RR. However, the rear side is not limited in such a manner.Instead, the rear side may also be formed so that the rear suctionchambers 18 and the shaft hole 12 a are communicated by communicationpassages through an intake groove, the shaft hole 12 a and the rearcylinder bores 29 are communicated by intake passages, and refrigerantis drawn from the rear suction chamber 18 into the rear cylinder bores29 through the communication passages, the intake groove of the rearrotary valve RR, and the intake passages.

In the embodiment described above, the suction port 44 is formed in thefront cylinder block 11. The suction port 44 may be formed in anotherportions in the housing H, for example, in the rear cylinder block 12.

In the embodiment described above, the refrigerant that has passedthrough the suction port 44 is supplied to the front suction chambers 17and the rear suction chambers 18 through the suction passage 43 formedin the cylinder blocks 11 and 12. However, the refrigerant that passesthrough the suction port 44 may be supplied to the front suctionchambers 17 and the rear suction chambers 18 through the swash platechamber 25.

In the embodiment described above, each of the three front dischargechambers 40 is arranged between adjacent front cylinder bores 28.However, the front discharge chambers 40 may be collectively formed atone or two locations. In this configuration, as shown in FIG. 10, a partof the intake groove 22 a is formed to have a ring shape that extendalong an entire peripheral surface of the rotation shaft 22 closer to afront end of the compressor.

Further, each of the three rear discharge chambers 42 is arrangedbetween adjacent rear cylinder bores 29. However, the rear dischargechambers 42 may be collectively formed at one or two locations.

In the embodiment described above, three rear suction chambers 18 areformed, and each rear suction chamber 18 is arranged between adjacentrear cylinder bores 29. Instead, the rear suction region may be formedby just the rear housing suction chamber 19, and the rear suctionchamber 18 may be collectively formed at one or two locations.

In the embodiment described above, the front suction chamber 17 that isin communication with the suction passage 43 has a greater volume thanthe other two front suction chambers 17. Instead, the volume of each ofthe other two front suction chambers 17 may be greater than the volumeof the front suction chamber 17 that is in communication with thesuction passage 43. In such a structure, refrigerant is directlysupplied from the suction passage 43. Thus, the front suction chambers17 that are in communication with the suction passage 43 may have asmall volume so that the refrigerant is smoothly supplied to the frontcylinder bores 28. In contrast, in the other two front suction chambers17, refrigerant is first supplied to the accommodation chamber 13 cbefore being supplied to the front cylinder bores 28. Thus, refrigerantis smoothly supplied to the front cylinder bores 28. This ensures alarge volume and supplies a greater amount of refrigerant.

The three front suction chambers 17 may have the same volume.

In the embodiment described above, the front suction chambers 17 and thefront discharge chamber 40 are formed extending over both of the fronthousing 13 and the cylinder block 11 but may be formed in only thecylinder block 11.

In the embodiment described above, the rear suction chambers 18 and therear discharge chamber 42 are formed extending over both of the rearhousing 14 and the cylinder block 12 but may be formed in only thecylinder block 12.

In the embodiment described above, the swash plate compressor isembodied in the double-headed piston type swash plate compressor.However, the swash plate compressor may be changed to a single-headedpiston type swash plate compressor including a single-headed pistonconnected with the swash plate 24 instead of the double-headed piston30.

Explanation of Reference Numerals

RF . . . front rotary valve serving as rotary valve, 10 . . .double-headed piston type swash plate compressor, 11 and 12 . . .cylinder block, 11 a and 12 a . . . shaft hole, 17 . . . front suctionchamber, 18 . . . rear suction chamber, 22 . . . rotation shaft, 22 a .. . intake groove, 24 . . . swash plate, 25 . . . swash plate chamber,26 and 27 . . . thrust bearing, 28 . . . front cylinder bore serving ascylinder bore, 28 b . . . front discharge chamber serving as dischargechamber, 29 . . . rear cylinder bore serving as cylinder bore, 29 b . .. rear discharge chamber serving as discharge chamber, 30 . . .double-headed piston, 32 and 33 . . . external pipe, 40 . . . frontdischarge chamber serving s discharge chamber, 42 . . . rear dischargechamber serving as discharge chamber, 43 . . . suction passage, 44 . . .suction port, 50 a . . . suction chamber communication passage, 50 b . .. front bore communication passage, 60 . . . first recess, 61 and 66 . .. second depression, 62 . . . suction chamber communication passage

1. A swash plate compressor comprising: a cylinder block including ashaft hole, cylinder bores, a swash plate chamber and a suction chamber,wherein the shaft hole extends through the cylinder block, the cylinderbores are arranged along a circumferential direction around the shafthole, and the suction chamber is arranged in a space between theadjacent cylinder bores and is separated from the swash plate chamber; aswash plate accommodated in the swash plate chamber; pistons connectedwith the swash plate and respectively arranged in the cylinder bores; arotation shaft arranged in the shaft hole and operative to rotateintegrally with the swash plate; and a rotary valve provided with therotation shaft to rotate integrally with the rotation shaft; wherein thecylinder block includes a suction chamber communication passage thatdefines a communication path between the suction chamber and the theshaft hole, and bore communication passages that define independentcommunication paths between the cylinder bores and the shaft hole,wherein the rotary valve rotates integrally with the rotation shaft toprovide sequential communication between the suction chambercommunication passage and the bore communication passages.
 2. The swashplate compressor according to claim 1, wherein the suction chamberincludes a plurality of suction chambers, each of the plurality ofsuction chambers is arranged between a circumferentially adjacent pairof the cylinder bores, the suction chamber communication passageincludes a plurality of suction chamber communication passages thatprovide independent communication between the suction chambers and theshaft hole.
 3. The swash plate compressor according to claim 2, whereinthe cylinder block includes a plurality of discharge chambers, each ofthe discharge chambers is arranged in a space between adjacent cylinderbores.
 4. The swash plate compressor according to claim 3, wherein thedischarge chambers are arranged outward in a radial direction of thecylinder block from the suction chambers.
 5. The swash plate compressoraccording to claim 1, wherein the cylinder block includes a suction portto which an external pipe is connected, and a suction passage thatprovides communication between the suction port and the suction chamber,the suction passage is separated from the swash plate chamber.
 6. Theswash plate compressor according to claim 1, wherein the suction chambercommunication passage is a recess formed in an inner wall of the shafthole, the recess including an open end in communication with the swashplate chamber, a thrust bearing is arranged between the swash plate andthe open end of the recess, and the thrust bearing closes the open endof the recess.
 7. The swash plate compressor according to claim 1,wherein the suction chamber communication passage includes a firstrecess and a second recess, the first recess formed in an inner wall ofthe suction chamber, the first recess including an open end, which openstoward an end face of the cylinder block in an axial direction, thesecond recess formed in an inner wall of the shaft hole, the secondrecess including an open end in communication with the swash platechamber, a thrust bearing is arranged between the swash plate and theopen end of the second recess, and the thrust bearing closes the openend of the second recess.
 8. The swash plate compressor according toclaim 1, wherein the cylinder bores are three cylinder bores.